[PATCH] dmaengine: edma: No need save/restore interrupt flags during spin_lock in IRQ

[PATCH] dmaengine: edma: No need save/restore interrupt flags during spin_lock in IRQ

[Joel Fernandes]

The vchan lock in edma_callback is acquired in hard interrupt context. As
interrupts are already disabled, there's no point in save/restoring interrupt
mask bit or cpsr flags.

Get rid of flags local variable and use spin_lock instead of spin_lock_irqsave.

Signed-off-by: Joel Fernandes <joelf@ti.com>
---
 drivers/dma/edma.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
index 91849aa..25a75e2 100644
--- a/drivers/dma/edma.c
+++ b/drivers/dma/edma.c
@@ -638,7 +638,6 @@ static void edma_callback(unsigned ch_num, u16 ch_status, void *data)
 	struct edma_chan *echan = data;
 	struct device *dev = echan->vchan.chan.device->dev;
 	struct edma_desc *edesc;
-	unsigned long flags;
 	struct edmacc_param p;
 
 	edesc = echan->edesc;
@@ -649,7 +648,7 @@ static void edma_callback(unsigned ch_num, u16 ch_status, void *data)
 
 	switch (ch_status) {
 	case EDMA_DMA_COMPLETE:
-		spin_lock_irqsave(&echan->vchan.lock, flags);
+		spin_lock(&echan->vchan.lock);
 
 		if (edesc) {
 			if (edesc->cyclic) {
@@ -665,11 +664,11 @@ static void edma_callback(unsigned ch_num, u16 ch_status, void *data)
 			}
 		}
 
-		spin_unlock_irqrestore(&echan->vchan.lock, flags);
+		spin_unlock(&echan->vchan.lock);
 
 		break;
 	case EDMA_DMA_CC_ERROR:
-		spin_lock_irqsave(&echan->vchan.lock, flags);
+		spin_lock(&echan->vchan.lock);
 
 		edma_read_slot(EDMA_CHAN_SLOT(echan->slot[0]), &p);
 
@@ -700,7 +699,7 @@ static void edma_callback(unsigned ch_num, u16 ch_status, void *data)
 			edma_trigger_channel(echan->ch_num);
 		}
 
-		spin_unlock_irqrestore(&echan->vchan.lock, flags);
+		spin_unlock(&echan->vchan.lock);
 
 		break;
 	default:
-- 
1.7.9.5

[PATCH] dmaengine: edma: No need save/restore interrupt flags during spin_lock in IRQ

[Vinod Koul]

On Thu, Apr 17, 2014 at 12:58:33AM -0500, Joel Fernandes wrote:
> The vchan lock in edma_callback is acquired in hard interrupt context. As
> interrupts are already disabled, there's no point in save/restoring interrupt
> mask bit or cpsr flags.
> 
> Get rid of flags local variable and use spin_lock instead of spin_lock_irqsave.

Applied, thanks

-- 
~Vinod

> 
> Signed-off-by: Joel Fernandes <joelf@ti.com>
> ---
>  drivers/dma/edma.c |    9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
> index 91849aa..25a75e2 100644
> --- a/drivers/dma/edma.c
> +++ b/drivers/dma/edma.c
> @@ -638,7 +638,6 @@ static void edma_callback(unsigned ch_num, u16 ch_status, void *data)
>  	struct edma_chan *echan = data;
>  	struct device *dev = echan->vchan.chan.device->dev;
>  	struct edma_desc *edesc;
> -	unsigned long flags;
>  	struct edmacc_param p;
>  
>  	edesc = echan->edesc;
> @@ -649,7 +648,7 @@ static void edma_callback(unsigned ch_num, u16 ch_status, void *data)
>  
>  	switch (ch_status) {
>  	case EDMA_DMA_COMPLETE:
> -		spin_lock_irqsave(&echan->vchan.lock, flags);
> +		spin_lock(&echan->vchan.lock);
>  
>  		if (edesc) {
>  			if (edesc->cyclic) {
> @@ -665,11 +664,11 @@ static void edma_callback(unsigned ch_num, u16 ch_status, void *data)
>  			}
>  		}
>  
> -		spin_unlock_irqrestore(&echan->vchan.lock, flags);
> +		spin_unlock(&echan->vchan.lock);
>  
>  		break;
>  	case EDMA_DMA_CC_ERROR:
> -		spin_lock_irqsave(&echan->vchan.lock, flags);
> +		spin_lock(&echan->vchan.lock);
>  
>  		edma_read_slot(EDMA_CHAN_SLOT(echan->slot[0]), &p);
>  
> @@ -700,7 +699,7 @@ static void edma_callback(unsigned ch_num, u16 ch_status, void *data)
>  			edma_trigger_channel(echan->ch_num);
>  		}
>  
> -		spin_unlock_irqrestore(&echan->vchan.lock, flags);
> +		spin_unlock(&echan->vchan.lock);
>  
>  		break;
>  	default:
> -- 
> 1.7.9.5
> 

--